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1.
《中国海洋大学学报(英文版)》2015,(5)
A Glycoside hydrolase(GH) typically contains one catalytic module and varied non-catalytic regions(NCRs). However, effects of the NCRs to the catalytic modules remain mostly unclear except the carbohydrate-binding modules(CBMs). Aga G4 is a GH16 endo-β-agarase of the agarolytic marine bacterium Flammeovirga sp. MY04. The enzyme consists of an extra sugar-binding peptide within the catalytic module, with no predictable CBMs but function-unknown sequences in the NCR, which is a new characteristic of agarase sequences. In this study, we deleted the NCR sequence, a 140-amino acid peptide at the C-terminus and expressed the truncated gene, aga G4-T140, in Escherichia coli. After purification and refolding, the truncated agarase r Aga G4-T140 retained the same catalytic temperature and p H value as r Aga G4. Using combined fluorescent labeling, HPLC and MS/MS techniques, we identified the end-products of agarose degradation by r Aga G4-T140 as neoagarotetraose and neoagarohexaose, with a final molar ratio of 1.53:1 and a conversion ratio of approximately 70%, which were similar to those of r Aga G4. However, the truncated agarase r Aga G4-T140 markedly decreased in protein solubility by 15 times and increased in enzymatic activities by 35 times. The oligosaccharide production of r Aga G4-T140 was approximately 25 times the weight of that produced by equimolar r Aga G4. This study provides some insights into the influences of NCR on the biochemical characteristics of agarase Aga G4 and implies some new strategies to improve the properties of a GH enzyme. 相似文献
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ZHANG Li LU Xinzhi HAN Feng MA Cuiping and YU Wengong* Marine Drug Food Institute Ocean University of China Qingdao P.R. China 《中国海洋大学学报(英文版)》2007,6(1):80-84
1 Introduction Agarases produced by agar-degrading bacteria are classified into two groups based on their modes of action, namely, α-agarase and β-agarase. They hydrolyze α -1, 3 linkage and β-1, 4 linkage of agarose respectively (Duckworth and Turvey, 1969). Agarases are widely used in food, cosmetic and medical industries for the produc-tion of oligosaccharides from agar (Kobayashi et al., 1997; Yoshizawa et al., 1995). Neoagaro-oligo- saccharides produced by β-agarase inhibit the gro… 相似文献
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Lectins play a crucial role in the innate immunity of invertebrates and vertebrates by recognizing and disposing of pathogens.We obtained the complete cDNA of a C-type lectin(EALec1) from Epinephelus akaara using RACE.The complete EALec1 cDNA sequence was 827 bp.The 5-UTR and 3-UTR were 28 bp and 151 bp,respectively,in length.The sequence also contained a polyadenylation signal AATAAA and a poly(A) tail.The EALec1 cDNA encodes polypeptides with 215 amino acids,including a signal peptide of 31 amino acids.Th... 相似文献
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Dewi Seswita Zilda 《中国海洋大学学报(英文版)》2012,11(2):213-218
A total of 69 strains of thermophilic bacteria were isolated from water, soil and sediment samples from three Indonesia’s hot spring areas (Pantai cermin, Kalianda and Banyu wedang) by using Minimal Synthetic Medium (MSM). The extreme thermophile Brevibacillus sp. PLI-1 was found to produce extracellular thermophilic alkaline protease with optimal activity at 70℃ and pH 8.0-9.0. The molecular weight of the protease was estimated to be around 56 kD by SDS-PAGE. The maximum activity of the protease was 26.54 U mL-1. The protease activity did not decrease after 30 min and still retained more than 70% of relative activity after 60 min at 70℃ and pH 8.0. The ion Mg2+ was found to promote protease activity at both low and high concentrations, whereas Cu2+ and Zn2+ could almost completely inhibit the activity. Divalent cation chelator EDTA inhibited the enzyme activity by 55.06% ± 0.27%, while the inhibition caused by PMSF, Leupeptin, Pepstain A and Benzamidine were 66.78% ± 3.25%, 52.37% ± 0.25%, 62.47% ± 2.96% and 50.99% ± 0.24%, respectively. Based on these observations, the enzyme activity was conspicuously sensitive to the serine and cysteine protease inhibitors. All these results indicated that the protease isolated from the strain PLI-1 was a thermophilic protease and had a high-temperature stability and a pH stability. 相似文献
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Unbalanced parental contribution and small effective population size(N e)are common issues during the artifi cial breeding of marine bivalves.The impact of hatchery-spawning practices on parental contribution,effective population size,the N e/N ratio,and genetic diversity are largely unknown.To address this,we conducted a parentage analysis on a complete 3×3 diallel cross of clam M eretrix meretrix using eight microsatellite markers.The genetic diversity of the parents was higher than that of their respective offspring in most crosses(8/9).Sires or dams from the same family contributed unequally to the pool of offspring from a particular cross,and the same parent clam exhibited large variation in parental contribution among different crosses.The variance in male contribution was higher than that of the female contribution in most crosses,suggesting that male contribution was more skewed than for females.The N e/N ratio for nine crosses ranged from 0.58 to 0.86.There was no linear relationship between the sex ratio and the N e/N ratio(P0.05).Moreover,a sex ratio closer to one-to-one does not necessarily mean a larger effective population size.A solution to small effective population size in commercial breeding programs is increasing broodstock numbers and attempting to maintain a balanced sex ratio. 相似文献
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SUN Yuhao CAO Siqi ZHANG Yuying XUE Changhu XIAO Hang CHANG Yaoguang 《中国海洋大学学报(英文版)》2024,(1):209-215
Carrageenan is a highly sulfated polysaccharide alternating of 1,4-O-α-D-galactopyranose-2,6-sulfate(D2S,6S) and 1,3-O-β-D-galactopyranose-2-sulfate(G2S). λ-Carrageenases are desirable tools for λ-carrageenan degradation. Based on the genome mining, a novel λ-carrageenase Cgl150A＿Wa was cloned from the bacterium Wenyingzhuangia aestuarii and expressed in Escherichia coli. Cgl150A＿Wa was an endo-acting enzyme and exhibited its maximum activity at 30℃ and pH 8.0. By employing a glycomics strategy ... 相似文献
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Effects of fucoidan from Laminariajaponica on 2,4-dinitrochlorobenzene induced de-layed-type hypersensitivity (DTH) reaction and the serum levels of IgG, IgM, complement C3 and C4 were investigated in the present study. Results showed that oral administration of fucoidan atdose of 1.50 and 300 mg/(kg*d) for 9 days before the hapten challenge significantly inhibited 2,4-dinitrochlorobenzene induced delayed-type hypersensitivity reaction; and also inhibited the humoral immunity. Serum C3 and C4 levels were markedly reduced by fucoidan at dose of 1.50 and 300 mg/kg; and serum IgG and IgM levels were reduced by fucoidan at dose of 300 mg/kg. The inhibitory effects of fucoidan on delayed-type hypersensitivity suggested that it may be potential medication for chronic inflammatory diseases in the future. 相似文献
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《中国海洋大学学报(英文版)》2015,(6)
κ-carrageenan oligosaccharides exhibit various biological activities. Enzymatic degradation by κ-carrageenase is safe and controllable. Therefore, κ-carrageenases have captured more and more attentions. In this study, a κ-carrageenase encoding gene, cgk X, was cloned from Pseudoalteromonas sp. QY203 with degenerate and inverse PCR. It comprised an ORF of 1194 bp in length, encoding a protein with 397 amino acid residues. Cgk X is a new member of glycoside hydrolase family 16. The deduced amino acid sequence shared a high similarity with Cgk X of Pseudoalteromonas κ-carrageenase; however, the recombinant Cgk X showed different biochemical characteristics. The recombinant enzyme was most active at p H 7.0 and 55℃ in the presence of 300 mmol L~(~(-1))Na Cl. It was stable in a broad range of acidity ranging from p H 3.0 to p H 10.0 when temperature was below 40℃. More than 80% of its activity was maintained after being incubated at p H 3.6–10.0 and 4℃ for 24 h. Cgk X retained more than 90% of activity after being incubated at 40℃ for 1 h. EDTA and SDS(1 mmol L~(-1)) did not inhibit its activity. Cgk X hydrolyzed κ-carrageenan into disaccharide and tetrasaccharide as an endo-cleaver. All these characteristics demonstrated that Cgk X is applicable to both κ-carrageenan oligosaccharide production and κ-carrageenase structure-function research. 相似文献
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LIUGuo-ming ZHANGHeng-rong KONGQing-jun WUCheng-zhi GUOFeng ZHANGChao-fan 《东北亚地学研究》2004,7(2):156-160
Tianchi Volcano is the largest potential erupticve volcano in China. Analyzing these data on seismic monitoring, deformation observation and water chemistry investigation gained from the Tianchi Volcano Observatory (TVO), the authors consider that the Tianchi Volcano is in going into a new flourishing time. 相似文献
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The development of rural area in suburban(RAS) is comprehensively influenced by the mixed processes of non-farming, local urbanization and rural industrialization and has distinctive multifunctional features on the socioeconomic and resource utilization.Multifunctional reconstruction in the RAS is mainly manifested by changes in the quantity and structure of the construction land use(CLU). We took Tongshan District of Jiangsu Province as the study case. Following the logic of identifying, cluste... 相似文献
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Effects of DNA extraction and universal primers on 16S rRNA gene-based DGGE analysis of a bacterial community from fish farming water 总被引：3，自引：0，他引：3
Among many reports investigating microbial diversity from environmental samples with denaturing gradient gel electrophoresis (DGGE), limited attention has been given to the effects of universal primers and DNA extraction on the outcome of DGGE analysis. In this study, these effects were tested with 16S rRNA gene-based DGGE on a bacterial community from farming water samples. The results indicate that the number of discernable bands in the DGGE fingerprint differed with the primer pairs used; the bands produced by 63f/518r, 341f/926r and 933f/1387r primer pairs were obviously fewer than those by 968f/1401r. Also, we found that each DNA extraction method resulted in different community profiles, reflected by the number and intensity of bands in the DGGE fingerprint. Furthermore, the main bands (theoretically representing dominant bacteria) differed with the extraction methods applied. It is therefore believed that the effects of universal primers and DNA extraction should be given more attention and carefully chosen before performing an investigation into a new environment with DGGE. 相似文献
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An agar-degrading bacterium,designated as Pseudoalteromonas sp. NJ21,was isolated from an Antarctic sediment sample. The agarase gene a ga1161 from Pseudoalteromonas sp. NJ21 consisting of a 2 382-bp coding region was cloned. The gene encodes a 793-amino acids protein and was found to possess characteristic features of the Glyco_hydro_42 family. The recombinant agarase(r Aga1161) was overexpressed in Escherichia coli and purified as a fusion protein. Enzyme activity analysis revealed that the optimum temperature and pH for the purified recombinant agarase were 30–40°C and 8.0,respectively. rAga1161 was found to maintain as much as 80% of its maximum activity at 10°C,which is typical of a coldadapted enzyme. The pattern of agar hydrolysis demonstrated that the enzyme is an β-agarase,producing neoagarobiose(NA2) as the final main product. Furthermore,this work is the first proof of an agarolytic activity in Antarctic bacteria and these results indicate the potential for the Antarctic agarase as a catalyst in medicine,food and cosmetic industries. 相似文献
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Glacial lake outburst floods(GLOFs)represent one of the most serious hazard and risk in deglaciating high mountain regions worldwide and the need for GLOF hazard and risk assessment is apparent.As a consequence,numerous region-and nation-wide GLOF assessment studies have been published recently.These studies cover large areas and consider hundreds to thousands of lakes,prioritizing the hazard posed by them.Clearly,certain simplification is required for executing such studies,often resulting in neglecting qualitative characteristics which would need manual assignment.Different lake dam types(e.g.,bedrock-dammed,moraine-dammed)are often not distinguished,despite they control GLOF mechanism(dam overtopping/dam breach)and thus GLOF magnitude.In this study,we explore the potential of easily measurable quantitative characteristics and four ratios to approximate the lake dam type.Our dataset of 851 lakes of the Cordillera Blanca suggests that while variances and means of these characteristics of individual lake types differ significantly(F-test,t-test),value distribution of different geometrical properties can’t be used for the originally proposed purpose along the spectra.The only promising results are obtained for extreme values(selected bins)of the ratios.For instance,the low width to length ratio indicates likely morainedammed lake while the high value of ratio indicating round-shape of the lake indicates increased likelihood of bedrock-dammed lake.Overall,we report a negative result of our experiment since there are negligible differences of relative frequencies in most of the bins along the spectra. 相似文献
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1 INTRODUCTION Lectins have been regarded as having a puta- tive role in non-self recognition in vertebrate and invertebrate immunities (Arason, 1996; Matsushita, 1996; Olafsen, 1996; Vasta et al., 1999; Wilson, et al., 1999; Marques and Barracco, 2000). … 相似文献
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Synedra ulna var, repanda Q. X. Wang ＆ Q. M. You, a new variety of Synedra （Bacillariophyta） from Xinjiang, China, is described and illustrated, and the characteristic of the variety： includes undulate-linear valves and straight pseudoraphe, differs from other species of Synedra. 相似文献
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The pigments in Laminariajaponica was extracted with six organic solvents and analyzed in spectroscopy analysis. The extractions conditions were screened by an orthogonal test and the quantity of extracted pigments was determined spectroscopically. The results show that： （1） among the six organic solvents, acetone was the most effective one for the extraction; （2） the optimum extraction conditions were as follows： the ratio of S/M （solvent volume/ material weight） was 30 ml/g; fresh seaweed was extracted 2 times in 2 h; （3） the average total content of pigments was 1.85 mg/g （calculated with dry L. japonica）. 相似文献
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Synedra ulna var. repanda Q. X. Wang & Q. M. You, a new variety of Synedra (Bacillariophyta) from Xinjiang, China, is described and illustrated, and the characteristic of the variety: includes undulate-linear valves and straight pseudoraphe, differs from other species of Synedra. 相似文献